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1 Leaves bipinnate, each pinna fully divided into distinct pinnules, the larger pinnules 3-7 cm long and 0.7-2.0 cm wide; spores borne on modified pinnae in the terminal portion of the leaf blade; veins of each pinnule 2× Y-forked (thus each vein reaching the margin as 4 final veinlets), each final veinlet making a fine tooth, thus the pinnule margins finely serrulate
1 Leaves pinnate-pinnatifid, each pinna additionally pinnatifid but not divided into distinct pinnules; spores borne either on specialized leaves that are normally wholly fertile (lacking flat, blade-like sterile pinnae), or hemidimorphic (juvenile leaves with only sterile pinnae, adult leaves with both sterile and fertile pinnae, the fertile pinnae borne in the middle of the leaf with sterile pinnae above and below; photosynthetic (sterile) pinnae lacking tufts of hairs; veins of each pinna lobe 1× Y-forked (thus each vein reaching the margin as 2 final veinlets), the final veinlets not creating a tooth, thus the pinna lobes entire to obscurely crenulate.
..2 Plants with hemidimorphic leaves (juvenile leaves with only sterile pinnae; adult leaves with both sterile and fertile pinnae, the fertile pinnae borne in the middle of the leaf with sterile pinnae above and below); photosynthetic (sterile) pinnae lacking tufts of hair on the lower side of the junction of the pinna and the rachis; [usually upland]
..2 Plants with dimorphic leaves (each leaf normally either completely photosynthetic or completely fertile); photosynthetic (sterile) pinnae with tufts of reddish hairs near the junction with the rachis; [usually of wetlands, or in mesic soils, or drier soils with seasonal and subterranean seepage]